It is sometimes required in an underground mine, to provide access from a lower level L thereof to an upper level U thereof, as shown in FIG. 1. A mine owner may request that a raise excavation R be created from the lower level L to the upper level U, which is of a certain size/configuration and length. The raise R may be used to serve a variety of purposes such as air ventilation, secondary personnel access/egress or as material dump chutes.
To create the raise excavation R, a pilot or access drift A is first excavated from the main mine drift D to the proposed raise location. This provides access to the raise for both personnel and muck removal equipment (not shown). As can be seen in FIG. 1, a muck pile M typically forms at the bottom of the raise R as it is being excavated.
An additional excavation N is typically made into the pilot or access drift A immediately adjacent to the raise location, to install an elevated working nest or parking area P for raise climbing equipment commonly referred to as a ‘raise climber’ 10. The raise climber 10 travels along a rail 12 and is used to start and muck the raise excavation R as is well known in the art. As the raise R is excavated, muck piles M accumulate at the bottom of the raise R and are then removed. The additional excavation N enables the raise climber 10 to retreat into the access drift A and avoid contact with the falling muck (rock) which occurs after a blast or when scaling.
To assist personnel in loading/unloading and entering/exiting the raise climber 10, a suspended deck, typically made of timber, is hung at the proposed parking area P. The decking is suspended using a series of chains/turnbuckles or other devices. The lower level of the access drift A is then clear for access by the mucking equipment so that the material can be removed as required. The parking area P can also be used by personnel to load supplies and to move into and out of the site.
A typical process for excavating a raise R includes driving the raise climber 10 to the face of the raise R, drilling a round of holes, loading the holes with explosives, returning to the parking area P, detonating the explosives, clearing the muck, adding rail 12 as necessary, and repeating until the raise R reaches the upper level U.
Problems with traditional parking areas P at raise excavation sites, e.g. as shown in FIG. 1, are that it is i) costly to excavate; ii) cannot be reused for any beneficial purpose once the raise R has been excavated; and iii) due to the relatively large excavation required, there is an added measure of instability in the parking area P that needs to be rectified with additional rock stabilization methods. As such, this upper area (excavation) N has no value after the raise excavation is complete.
Another problem is that, although moving the raise climber 10 into the additional excavation N and above the parking area P removes the raise climber 10 from the direct path of the falling debris accumulating in the muck pile M, both the raise climber 10 and the decking timber may still interfere with the muck removal equipment and would require regular maintenance and repairs. The elevated work platform also introduces safety concerns as access for workers and materials is provided via a ladder way. The raise end of the platform has limited protection as the raise climber 10 traverses the area on its way to and from the raise R.
Yet another problem with the excavation site shown in FIG. 1 is that the raise climber 10 is idle while blast material is being removed from the site. Moreover, when multiple raises are needed in the same mine, multiple raise climbing systems may be employed to excavate each site simultaneously, or a single unit used independently and in sequence, when in close proximity to each other, which can be time consuming and expensive.
It is therefore an object of the following to obviate or mitigate the above-noted disadvantages.